Thermal diffusion apparatus



April 23, 1957 J. w. THOMAS THERMAL DIFFUSION APPARATUS Original Filed,Aug. 12, 1953 INVENTOR. JOHN. W. THOMIIS WQQM HTTORNE Y5 2,789,946 rTHERMAL DIFFUSION APPARATUS John W. Thomas, Cleveland, Ohio, assignor toThe Standard Oil Company, Cleveland, Ohio, a corporation of OhioOriginal application August 12, 1953, Serial No. 373,807. Divided andthis application June 17, 1954, Serial No. 437,549 1 3 Claims. (Cl.210-176) The present invention relates to apparatus for the separationor concentration of fluids by thermal diffusion and more particularly toconstructions designed to compensate for the difference in thermalexpansion and contraction of the wall members of such apparatus and tofacilitate their assembly.

This application is a division of application Serial No. 373,807, filedAugust 12, 1953.

.111 subjecting fluids, i. e., mixtures of materials that are gaseous orliquid under the conditions of operation or liquids containing one ormore components dissolved or suspended therein, to thermal diffusion forthe purpose of separating the components thereof or obtaining fractionscontaining concentrations of one or more of the components that varyfrom those present in the original fluid, the fluid is passed through orconfined within a thermal dilfusion separation chamber defined byclosely and substantially equidistantly spaced surfaces, one of which ismaintained at a relatively higher temperature than the other in order toimpose a temperature gradient across the chamber. The width of thechamber, i. e., the spacing between the chamber-forming surfaces, is ofthe order of about 0.15 inch or less, preferably less than about 0.06 or0.08 inch in apparatus designed to subject liquids to thermal diffusion.For the thermal diffusion of gaseous mixtures, the width of the chambermay be considerably greater but is still preferably of the order of asmall fraction of an inch.

The construction and assembly of thermal diffusion apparatus meetingthese requirements has heretofore been attended with considerablydifficulty, particularly where the apparatus comprises a considerablenumber of flat wall members, the exterior surfaces of which form aseries of thermal diffusion separation chambers when they are boltedtogether with gaskets disposed between them. One of these diflicultieshas been due to the fact that when the apparatus is assembled, all ofthe wallmembers are at approximately room temperature, and when theapparatus is placed in operation, one of the wall members,

tus is assembled in the vertical position, considerable difficulty hasalso been experienced in maintaining the gaskets in their properposition until sufiicient pressure is applied thereto by adjacent wallmembers.

Similar difficulties have been encountered in the concentric tube typeof thermal diffusion apparatus. In view of the extremely small width ofthe thermal diffusion chamber, it is manifest that it is almostimpossible to provide a cylindrical gasket which at one and the sametime will have a sufficient wall thickness and compressibility tofacilitate insertion into the ends of the annular space between twoconcentric tubes, and once having been inserted, exert sufficientpressure against the inner surface of the outer tube and the outersurface of the inner tube to provide a seal that is leakproof when thetemperature conditions vary between conditions of equal temperature ofboth tubes and relatively high and low temperatures of the inner andouter tubes, respectively, or vice versa, during operation. Thisdifficulty is further aggravated by the fact that when a temperaturegradient is applied across the annular separation chamber, i. e., whenone of the tubes is heated to a temperature considerably higher than theother, the relatively highly heated tube will expand and thus give riseto leakage of fluids in the chamber past the gasket unless the gasket isprefabricated and fitted with extreme accuracy.

The present invention is directed to constructions designed to obviatethese problems.

In accordance with the present invention, thermal diffusion apparatus isprovided which comprises two or more wall members subject todifierential thermal expansion and contraction and having closely andsubstantially equidistantly spaced surfaces that define one or morethermal difiusion separation chambers. One or more gaskets are disposedbetween and in contact withportions of the wall members to confine fluidwithin the chamber or chambers. The gasket-contacting portion orportions of one or more of the wall members are inclined at an obtuseangle to the chamber-defining surface or surfaces thereof. Thegasket-contacting portion or portions may also be recessed to facilitateretention of the gasket or gaskets in the desired position or positionsduring assembly of the apparatus and also to compensate for dimensionalchanges in the wall members during operation and, to make possible theuse of one or more gaskets hav ing a thickness considerably in excess ofthe spacing between the charnber-forming surfaces of the wall members.

The term recessed, as applied to a wall member herein, is intended tomean that the portion of the wall member referred to has an indentationin its surface which departs from the chamber-defining surface of saidwall member. Thus, in accordance with the invention, the recess of awall member having a plane chamber-defining surface is a surface portionat an obtuse angle to the plane of the chamber-defining surface, and therecess of a wallmember having a cylindrical chamber-defining surface isa conical surface portion, the mean diameter of whichis greater than thediameter of said cylindrical chamberdefining surface.

Where the wall members are flat and the chamber-defining surfaces aresubstantially parallel to one another, in accordance with the presentinvention, the gasket-contacting portion is recessed at an angle,preferably obtuse, to the surface thereof defining one side of thechamber. Where the gasket-contacting portion of a first wall member isrecessed at an obtuse angle, the gasket-contacting portion oftheadjacent wall member, i. e., the member having a surface defining theother side of the chamber, may be parallel to the recessedgasket-contacting portion of the first wall member, or substantiallyparallel to its own chamber-forming surface, I

Where apparatus comprises inner and outer wall members, thechamber-defining surfaces of which are cylindrical and concentric toform an annular separation chamber, the gasket-contacting portion of theouter wall member may be provided, at one or both ends, with a conicalrecess having a diameter greater than the diameter of itschamber-forming surface. The corresponding end or ends of the innerwallmember may be of the same, diameter as the chamber-forming surfacethereof, have Patented Apr. 23, 1957 The advantages and utility oftheapparatusof the.

invention will" become further apparentfrom the following'detaileddescription madewith reference to the accompanying drawing wherein:

Figure 1 is a cross-sectional view in elevation through one preferredembodiment of-the apparatus of the inventiong Figure 2'is a similar viewthroughanother preferred embodiment of the invention;

Figures 3, 4 and-5 arefrag-mentary viewsof similar apparatus, on asomewhat larger'scale; illustrating severalof the alternativeembodiments of the invention;

' Figurei6' is a-cross-sectional view inelevation of a tubutar: type.thermal diffusion apparatus employing the principles of the invention;and" Figures 7, Sand -9 are fragmentaryviews, on a somewhat largerscale,- illustrating several alternative embodiments of the inventionillustrated in-Figureo;

The apparatus illustrated: in Figure 1 comprises two wall membersIOi-and 11' having closely and substantially equidistantlyt-spacedsurfaces 12 and 14; defining a thermal diifusionseparation chamber. 16,and agasket 17 between andtin contact with the portions 1 9 and: 20thereof. The wall! members are. provided with coilst21 or other suitable.meansfor maintaining-thesurfaces 12 andi14 at=different temperaturesand one. or both. of the wall members areprovided with ports 22 forintroducing the fluid.

' ln thistxcmbodiment the gasket-contacting portion 19 ofthe-walhmember,isat,an cbtuse angle (180 0) to the chambenforming surface 12, and thegasket-contacting portion of the wall member 11 is substantiallyparallel to the'portion 19. The gasket 17 is substantially thickerthanthe width of the separation chamber 16. It ispreferred, in thisembodiment, that the wall member 10 be the wall member that ismaintained at the relatively higher, temperature during operation of thethermal difiusionseparation chamber Iii-inasmuch assuch a choiceinvolves amiuimumpossibility of leakage past the gasket 17 duringoperation or during any interruptions in operation. It is furtherpreferred that the angle 9 bean angle having a tangent. equal or closeto the ratio of the chamber thickness to the chamber width. If the.resiliency of the gasket is fairly large, the angle 6 may be variedoverarrange greater than wouldvbe-p ossible if the gasket were nottooresilient, such as 150%.

To illustrate the manner in which this construction compensates, for;vthe differential expansion and contraction of the wall members 10 and11, the contractionof the wall member 10 upon cooling from the operatingtemperature is,illustrated, on an exaggerated scale, by dashedlines2i,ands26 which shows an increase in chamber thickness, lt willtbe notedthat upon contraction of the walLmember 10, which shows an increase inchamber width, ,the gasket con=tacting portion 19 thereof will tend tocreep inwardly along the surface of the gasket 17 rather. than to reducethe pressure thereon. This means that even with fluctuating temperaturesthe spacing between gasket; surfaces 191 and 20; will remain constant.Thegasketlogadnill, thereforc,.remain constant, thereby assuring aleakproof seal. In addition, the recessing of thergasketecontactingportion 20 of the wall member 11 assistsdnimaintaining the gasket 17 inthe desired position-during assembly of the wall members into the posi-Lion-shown.

The embodiment illustrated in Figure 2 likewise comprises wall-members10a. and 11a havingsurfaces forminga separation chamber 12a'and a gasket17a. In thisembodiment the wall member-11a isrecessed at 2011 to form agasket-contacting portion that is substantially paralleltoitschamber-formingsurface-14a; The gasket contacting surface 19a ofthe wall member 10a is in substantially the same plane as itschamber-forming surface 12a.

In this embodiment it is prefcrred that the wall member 10a be the wallmember that is maintained at a relatively highertemperaturethan-the-wall-member 11a for the. reason. that less.gasket-material makes. Contact with;

the portion,.19a of'ithe: relatively hot. wall: member 10a than with therecessed portion 20a of the wall member 11a and is, therefore, lesssubject to deterioration by heater totransfer of heat (through thegasket to the and wherein one wallmember is'recessed atanangle 9 that isobtuse to its surface formingtlheseparation chamber 16c, and the other-Willll member 100 is substantially plane the gasket-contactingportionthereof being inthe same plane with its chamberformingsurface12c.

Figure-5 illustrates an embodiment similar to that of Figure 1 in which:the spacing='between-the recessed gasket-contacting portioniiid of thewall member 11:! and the ga-skeeoontacting portion 19d'ofthe=wall"member lfld, and therefore also the operative thickness of thegasket 17d, are substantially equalto the width of the chamber 16d:Whilethis embodiment does not have the advantage of utilizing a gasketsubstanti lly thicker than the-width of-the-chamber, it possesses all ofthe thermal expansion and contraction compensating features of theembodimentill-ustra-tedin Figure 1.

Figure 6' illustrates a \tubular type of thermaldiffusion apparatuscomprising an'inner wall member 30; an-outer wall member 31,- the outersurface-32 of the inner member 30 and the inner surface 34 of the outermember 31- being concentric *and' forming anannularseparation chamber36; The upper end of the outer member 31 is shown as having a co-nicallyrecessed gasket-contact ing portion 37 for receiving a gasket 39, andtheinner member 30lis provided; at the corresponding end, witha radiallyprotruding conical surface 40 thatis complementary to the recessedconical surface 37 of the outer member 31. At the lower end, theseparation chamber 36' is sealed by a 'cylindric-aigasket 41 havinga'thickness approximately equal to the width of'the separation chamber 36.It is to bcunderstood, of course, that the apparatus illustrated inFigure 6- is furtherprovidedwith suitable ports; such as'shown at 42,for the introduction of a fluid into the separation chamber 36' and theremoval therefrom of separated fractions, as well as with any desiredmeans for maintainingthe chamberfonning surfaces 32'iand' 34- atdifferent-temperatures to impose a [temperature gradient across thechamber.

In this embodiment of the-invention it will be apparent that it isnecessary to provide for relative expansion and contraction of the wallmembers 39 and 31 at only one end if the wall members are more or lessrigidly joined at the other end. It will be apparent, for example,

[that if Figure 6- represents the relative positions of the In theconstruction illustrated sliding of the gasket-contacting portion 40over the surface of the gasket 39 and to a minor extent in applyingsomewhat greater pressure to the gasket 39. In any event, the necessityof providing a gasket of such extremely small thickness as that ofgasket 41 is avoided inasmuch as the thickness of the gasket 39 may beseveral times the width of the chamber 36.

Figures 7, 8 and 9 illustrate several alternative embodiments of theinvention illustrated in Figure 6. In Figure 7 the construction of theouter wall member 31a is identical to that shown in Figure 6 but theinner wall member 30a lras a gasket-contacting surface 40a of the samediameter as: the chamber-forming surface 32a and the shape of the gasket39a is correspondingly altered. In Figure 8 of the inner Wall member300: is substantially similar to that illustrated in Figure 7 but theouter wall member 31a is provided with a cylindrical recess 37a designedto accommodate a cylindrical gasket 39b 'having a thicknesssubstantially greater than the width of the annular separation chamber36. In order to limit the upward movement of the gasket material 39a and39b as a result of the contraction of the outer tube 31, an annular ring43 may be placed at the top of the inner (tube 30a.

In Figure 9, the outer wall member 3112 is substantially similar to thatillustrated in Figure 8 and the inner wall member 3% is provided with aradially protruding cylindrical surface 40b having a diameter smallerthan the diameter of the cylindrical recessed portion 37a of the outerwall member and a gasket 396 is interposed between the portions b and37a of the members 30b and 31a, respectively.

It is to be understood, of course, that any :two of the embodimentsillustrated in Figures 6, 7, 8 and 9 may be combined in a singleapparatus. Thus, the structures shown in Figures 7 and 8 may replace thestructure shown in the lower end of Figure 6, and the structures shownin Figures 7, 8 and 9 may replace the structure shown at the top of theapparatus in Figure 6.

It is further to be understood that innumerable modifications will atonce become apparent to those skilled in the art upon reading thisdescription. All such modifications are intended to be included withinthe scope of the invention as defined in the appended claims.

I claim:

1. Thermal diffusion apparatus comprising two wall members subject todifferential thermal expansion and contraction and having closely andsubstantially equidistantly spaced surfaces defining a thermal diifusionseparation chamber, said chamber defining wall surfaces being flat andsubstantially parallel to one another, and a gasket between and incontact with portions of said Wall members for confining fluid withinsaid chamber, the gasket-contacting portion of one of the wall membersbeing at an obtuse angle to the chamber-defining surface of said one ofthe wall members, at least a part of said gasket contacting portion ofsaid one wall member being spaced from the gasket-contacting portion ofthe other wall member a greater distance than the spacing between saidsurfaces, said gasket having one side engaging said part of saidgasket-contacting portion of said one wall rnember and another side ofsaid gasket engaging the gasket-contacting portion of said other wallmember.

2. Thermal difiusion apparatus comprising two wall members subject todifferential thermal expansion and contraction and having closely andsubstantially equi distantly spaced surfaces defining a thermaldiffusion separation chamber, said wall members and chamber definingwall surfaces there-of being concentric and form ing an annularseparation chamber, and a gasket between and in contact with portions ofsaid wall members for confining fluid within said chamber, thegasket-contacting portion of one of the wall members being substantiallyconical and disposed :at an obtuse angle to the chamberdefining surfaceof said one of the wall members, at least a part of saidgasket-contacting portion of said one wall member being spaced from thegasket-contacting portion of the other wall member a greater distancethan the spacing between said surfaces, said gasket having one sideengaging said part of said gasket-contacting portion of said wall memberand having another side engaging the gasket-contacting portion of saidother wall member.

3. Thermal diffusion apparatus comprising two well members subject todiflerential thermal expansion and contraction and having closely andsubstantially equidistantly spaced surfaces defining a thermal diffusionseparation chamber, and a gasket between and in contact with portions ofsaid wall members for confining fluid within said chamber, thegasket-contacting portion of the wall member subject to the lower degreeof thermal expansion and contraction being an obtuse angle to thechamber defining surface thereof, at least a part of saidgasket-contacting portion of said one wall member being spaced from thegasket-contacting portion of the other wall member :a greater distancethan the spacing between said surfaces, the gasket having one sideengaging said part of said gasket-contacting portion of said one wallmember and having another side engaging the gasketcon-tacting portion ofsaid other wall member.

References Cited in the file of this patent UNITED STATES PATENTS1,312,913 Krause Aug. 12, 1919 1,830,205 McLa-i-ne Nov. 3, 19311,901,581 Chamberlain Mar. 14, 1933 2,541,069 Jones et al. Feb. 13, 19512,550,027 Thompson Apr. 24, 1951

1. THERMAL DIFFUSION APPARATUS COMPRISING TWO WALL MEMBERS SUBJECT TODIFFERENTIAL THERMAL EXPANSION AND CONTRACTION AND HAVING CLOSELY ANDSUBSTANTIALLY EQUIDISTANTLY SPACED SURFACES DEFINING A THERMAL DIFFUSIONSEPARATION CHAMBER, SAID CHAMBER-DEFINING WALL SURFACES BEING FLAT ANDSUBSTANTIALLY PARALLEL TO ONE ANOTHER, AND A GASKET BETWEEN AND INCONTACT WITH PORTIONS OF SAID WALL MEMBERS FOR CONFINING FLUID WITHINSAID CHAMBER, THE GASKET-CONTACTING PORTION OF ONE OF THE WALL MEMBERSBEING AT AN OBTUSE ANGLE TO THE CHAMBER-DEFINING SURFACE OF SAID ONE OFTHE WALL MEMBERS, AT LEAST A PART OF SAID GASKET CONTACTING PORTION OFSAID ONE WALL MEMBER BEING SPACED FROM THE GASKET-CONTACTING PORTION OFTHE OTHER WALL MEMBER A GREATER DISTANCE THAN THE SPACING BETWEEN SAIDSURFACES, SAID GASKET HAVING ONE SIDE ENGAGING SAID PART OF SAIDGASKET-CONTACTING PORTION OF SAID ONE WALL MEMBER AND ANOTHER SIDE OFSAID GASKET ENGAGING THE GASKET-CONTACTING PORTION OF SAID OTHER WALLMEMBER.